Automatic extraction of traces of slope failures from high accurate DEM using "Slit Method"

Abstract

An automatic method to extract traces of slope failures was established on the basis on the high accurate DEM of 2 meter mesh. The DEM was obtained using air laser scanning covering a rectangular area of 2 km x 1km, where numerous slope failures occurred triggered by heavy rainfall. Three criteria were used to determine concave slopes, which correspond to old slope failures. (i)existence of concave slopes, (ii)existence of scarplets, and (iii) circular shape of them, respectively. To obtain the fundamental data of slope changes, Laplacian values of elevations were calculated for the analyses. And "slit method" was used to judge circular topographic characteristics. Consequently, many concave topographies corresponding slope failures were effectively extracted using this method. Based on the topographic contour lines, this method was confirmed to be effective. This means that the method is more effective than that of air photo interpretation.